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USING D E L A Y E D S W E E P F O R M E A S U R E M E N T O F
RISETIMES A N D FALLTIMES
Risetimes and falltimes are generally measured by using the
10% and 9 0 % amplitude points as reference starting and
ending points for the rise or fall.
1. Apply the signal to the INPUT jack and set the vertical
MODE to the channel to be used.
Use the VOLTS/DIV and VARIABLE controls to obtain a
normal 6 divisions vertical amplitude waveform.
Using the • POSITION control, set the waveform posi-
tion in the central area of the screen vertically, that it to
coincide with the 1 0 0 % and 0 % lines on the C R T
screen.
Set the SWEEP TIME/DIV control to as high a speed as
possible consistent with observatin of both the 10%
and 9 0 % points.
Set the SWEEP VARIABLE to C A L position.
2. Set the B TRIG MODE to initiate the AFTER DELAY
mode of operation and HORIZ MODE to INT and adjust
the B SWEEP TIME/DIV for as short as possible an inten-
sified section of waveform.
3. Using the DELAY TIME MULT, adjust the waveform
such that the 1 0 % point is intensified and record the
dial reading.
4. Similarly, using the DELAY TIME MULT, adjust the 9 0 %
point so that it is intensified and record that dial reading
as well.
The pulse risetime (or falltime) is simply the difference
between the two dial settings times the A SWEEP
TIME/DIV control setting.
Using the formula:
Risetime = (2nd dial reading — 1st dial reading) x Delayed
sweep time (A SWEEP TIME/DIV setting)
-Rise time
Fig. 37
[ E X A M P L E ]
For the example, the first dial reading is 1.20 (10% point)
and the second is 7.38 (90% point) with the A SWEEP
TIME/DIV set at 2 /ts. (See Fig. 37)
Substituting the given value:
Risetime = (7.38 - 1 . 2 0 ) x 2 ( ^ = 1 2 . 3 6 (is
TIME
D I F F E R E N C E
M E A S U R E M E N T S
DELAYED SWEEP
Synchronized waveforms which are skewed in time can be
accurately measured using the delayed sweep.
1. Apply the two signals to the CH1 and CH2 INPUT jacks
setting the vertical MODE to DUAL and selecting either
ALT or CHOP display.
2. Set the SOURCE to the signal that is leading in phase
and adjust VOLTS/DIV and SWEEP TIME/DIV for easy
waveform observation.
Set the SWEEP VARIABLE control to C A L position.
3. Set the B TRIG MODE to initiate the AFTER DELAY
mode of operation. Set the HORIZ MODE to INT and ad-
just the B SWEEP TIME/DIV and DELAY TIME MULT to
make the intensified portion coincide with the rising
edge or falling edge of the waveform that is to be used
as the reference.
4. Set the HORIZ MODE to A L T and use the T R A C E
SEPARATION control to adjust the B sweep for easy
observation.
5. Using the DELAY TIME MULT adjust the pulse to any
convenient vertical graduation line and record the dial
reading at that point.
6. Using the DELAY TIME MULT adjust the corresponding
point on the second signal to the same vertical line and
record the reading of the dial at this point as well. The
time difference or skew of the two waveforms is then
the second dial reading minus the first dial reading
multiplied by the A SWEEP TIME/DIV control setting.
Using the formula:
Time difference = (2nd dial reading — 1st dial reading)
x Delayed sweep time (A SWEEP TIME/
DIV setting).
[EXAMPLE]
The reference signal dial reading is 1.00 while the second
dial reading is 5.34 with an A SWEEP TIME/DIV setting of
2 (is. (See Fig. 38)
Substituting the value:
Time difference = ( 5 . 3 4 - 1 . 0 0 ) x 2 (/*s) = 8.68 /ts
USING
Read the dial setting w h e n
- B s w e e p points of D E L A Y
" T I M E M U L T © and © are
in the s a m e position.
Fig. 3 8
2 9
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